As-Built and Post-treated Microstructures of an Electron Beam Melting (EBM) Produced Nickel-Based Superalloy
- PDF / 4,206,191 Bytes
- 14 Pages / 593.972 x 792 pts Page_size
- 39 Downloads / 222 Views
INTRODUCTION
ADDITIVE manufacturing (AM), commonly known as 3D printing, is a rapidly growing group of processing technologies comprehensively reviewed by Horn and Harrysson.[1] In AM, it is possible to produce geometrically complex components directly from computer-aided design (CAD) models.[2] The ease of manufacturing, compared to the traditional production routes, makes AM a promising emerging technology. Electron beam melting (EBM) and laser powder bed fusion (LPBF) are two commonly used AM technologies
SNEHA GOEL and SHRIKANT JOSHI are with the Department of Engineering Science, University West, 461 86 Trollhaˆttan, Sweden. Contact e-mail: [email protected] HITESH MEHTANI and INDRADEV SAMAJDAR are with the Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai, 400076 India. SHU-WEI YAO is with the School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an, 710049 China. UTA KLEMENT is with the Department of Industrial and Materials Science, Chalmers University of Technology, 412 96 Go¨teborg, Sweden. Manuscript submitted February 22, 2020; accepted September 17, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS A
based on powder bed fusion, as broadly reviewed by Frazier.[3] EBM makes use of a high-energy electron beam to selectively melt and consolidate appropriate regions of each layer of powder raked to build a component in layer-by-layer fashion.[4] EBM processing of nickel-based superalloys (example: Alloy 718) appears particularly promising to the aircraft engine industry,[5] which demands complex parts manufactured from difficult-to-machine materials. During EBM processing, individual layers undergo various processing steps, with the typical melting steps involving contour and hatch scanning as detailed in Reference 6. For every layer, the perimeter of the component(s), also known as contour, is typically melted by a ‘multi-spot’ melting strategy. During this step, the spot melting pattern is used to create a ‘frame’ of the component according to a pre-defined CAD geometry as elaborated in Reference 7. This step is followed by hatch melting, during which the beam typically scans in a raster pattern to consolidate the region(s) contained within the contour(s). In a word, the hatch melting melts the bulk material while the contour scanning provides adherence to component geometry.[8] The thickness of the contour region is thus fixed, but the extent of the hatch region depends on the overall component dimensions.[9] In case of thinner
sections, the microstructure of the contour thus becomes critical. It is worth mentioning that the order of contour and hatch scanning can be modified, and typically for EBM manufacturing of Alloy 718, the contour is melted before the hatch. Alloy 718 is a precipitation-hardened Ni-based superalloy, which is used in varied operating environments, such as for high temperature as well as cryogenic applications in diverse fields such as aerospace, oil and gas, nuclear industries, etc. Such extensive usage is at
Data Loading...
